I. Field of the Invention
This invention relates to mouse input devices for computer systems and, more particularly, to an improved method and apparatus for interfacing a mouse input device to a computer system by using an input channel designed for accepting potentiometer derived inputs.
II. Background Information
Low cost personal computers intended for use by beginning or unsophisticated computer users are commonly designed to employ the so-called "mouse-icon" user interface graphics. This type of user interface system allows the computer operator to select programs and generate input commands without knowledge or memorization of any special input command codes and sequences. The user simply calls up various graphic screen presentations containing instructional information and symbols called "icons." By using a two dimensional motion sensor such as a mouse track ball input device, the operator positions a cursor on the screen to selected icon symbols and operates one or more buttons on the mouse device to signal program selections or to otherwise generate computer input commands.
The computer system controls the screen position of the cursor based on movement commands generated through use of the mouse. The operator moves the mouse along a flat surface in order to rotate a track ball within the mouse casing, whereupon X and Y input commands are generated and supplied to the computer. The computer converts the mouse input commands into X and Y position signals and locates the cursor on the screen accordingly.
Low cost personal computer systems are generally designed to utilize a number of different types of input devices. For example, "joystick" input devices are frequently provided to enable the user to execute video game programs. The computer system usually is equipped with special interface devices to enable signals produced by a joystick controller and other specialized types of input devices to be converted into signals processable by the computer. Another common type of user input device supplied with a personal computer system is the so-called "paddle" controller. This type of device employs one or more slide-type potentiometers which are operated either by linear or rotational user actuated controls.
It is an object of the present invention to provide an improved method and apparatus for connecting a mouse-type input device to a computer system.
Another object is to provide an interfacing circuit of the type described which allows a mouse-type input device to be interfaced to the system via an existing, standard input channel designed for another type of input device.
Still a further object is to provide a circuit for interfacing a mouse-type input device to a computer system using an input channel designed for receiving potentiometer-generated input commands.
Additional objects and advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. The objects and advantages of the invention may be realized and obtained by means of the instrumentalities and combinations particularly pointed out in the appended claims.